Rotary heating furnace



March 1945; A. F. KRITSCHER ROTARY HEATING FURNACE Filed Nov. 30, 1943 3 Sheets-Sheet 2 March 13, 1945. A. F. KRITSCHER 2,371,335

ROTARY HEATING FURNACE Filed Nov. 30, 1943 Fig.5.

3 Sheets-Sheet 3 I j INVENTOR causing it to rotate or turn in its Patented Mar. 13, 1945 UNITED STATES. PA

OFFICE ROTARY HEATING FURNACE Andrew F. Kritscher, Ellwood City, Pat, assignor to National Tube New Jersey Company, a corporation of Application November 30, 1943, Serial No. 512,373

(crass-7) 12 Claims.

This; invention relates to rotary heating fur- ,naces ,for tubes. bars,-. and similar elongated articles which are commonly heated by passing .hem ,,through continuous heating furnaces where th ey.-,rest on bars duringtheir passage there- ;through. .The fuel economy of the furnace is vlow andthe lengthof the furnace is often not ,sufiiciently great to allow the tube to become evenly heated throughout. a As the tube rolls on the bars, those portionsof the tube in contact points. In many instances the combustion vol- Jame oft-hefurnace is insufiicient andthe tubes besides being spotted and unevenly heated have scale formedthereon. In the case of tubes which are being heated prior to rolling in a sinking mill,

To obtain satisfactory results .in

into the surface of the article.

. It is an object of this invention toprovidea furnace in which the tube is evenly heated by passage through the furnace.

-Another object is to provide a furnace wherein the tube cannot contact the refractory.

, These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

Y Figure l is a longitudinal cross-section of the furnace which shows schematically the wiring diagram for operating the furnace; Figure 2 is a cross-sectional view on the line II- II of Figure 1; .7

Figure 3 .is an end view showing the inlet side of the furnace; and 7 Figure 4 is an end view of the outlet side of the furnace.

Referring more particularly to the drawings, thereference numeral 2 indicates the walls-of thefurn'ace. As best shown-in Figure 2', the walls consist of top and bottom sections 4 and 6. Each section has a circular refractory lining 8 surrounding which is a circular insulating layer In on'the outside of which is a metal casing I2. The walls ,are "bound together hymeans of} hoops l4 As the article with the bars do not become sufficiently heated ,with the result that there, are black spots at those which encircle the casing iZat spaced intervals.

A hollow spindle shaft It extends longitudinally through the furnace and is supportedby means of bearings l8 outside the furnace. If necessary, additional bearings 20 may be provided within the furnace. Welded or otherwise fastened to the shaft l6is a plurality of turrets22, each of which ,is provided with a plurality of angularly spaced openings .24 for receiving the tube or other article ,to be heated. A plurality of driven rollers 26 passthrough the furnaceand are supported on cradle bearings 28 outside the furnace,. the rollers being provided with grooves for feeding the .tubeto and from the heating chamber 30. These rollers may be driven by any suitable means and,

as :shown, are rotated by means of a chain meshing with the sprocket 32- Brackets 34 attached tothe casing 12 provide means for lifting the top section 4 of the furnace from the lower section 6.

Burnertun'nels- 36 are provided along the length of the furnace for supplying heat thereto. Combustion air is provided to the burners by means of a blower (not shown), the suction end of which is connecteditothe shaft 16. In this man ner, the combustion air is preheated and the efficiency of the furnace increased. The inside contour gives swirling circulation'of the gases and provides ideal radiation and reradiation. It will beunderstood that all metallic parts within the furnace are made from a suitable heat resistant alloy. The shaft I6 is provided with a sprocket wheel tfi located outside of the furnace and which is rotated by a motor 40 through'thechain 42.

A normally closed switch 44 has a trigger 46 a in line with the furnace opening 48 through which the tube enters. The cam 5c of the switch is located outside of the furnace. At the other end of the furnace in line with the switch 44' is a normally open switch 52 having a trigger 54 in line with the entering tube X and a cam be located outside the furnace. "A limit'switch cam 58 is mounted on the turret shaft for movement therewith: A normally closedswitch Gil, having a triggerii'l and a cam 64, is located outsideth'e furnace with-its trigger in line with the outgoing tube whichleaves the furnace through an opening thatiis offset with respect to the opening 48. A time'switchiifi'is also provided in the controlcircuit for a purpose which will appear later. Power is provided. to the motor 40 from the power iihes'68, H1 and 12', through the power circuit which is provided with a line switch 14 and magnetic contactors 1B, the coil I8 of which is con-'- t t by the el c rcuit. in case of overload, an overload relay 8!] will open the contactor 82, thus preventing damage.

The operation of the furnace and control circuit therefor is as follows:

With the furnace in operation, heat is provided thereto through the burner tunnels 36, the amount of heat being controlled in accordance with the temperature desired in wthe furnace. when it is desired to feed a tubeTX to the furnace, the rollers 26 are caused to rotate feeding the tube into the furnace. As the tube .X enters the furnace, it depresses the trigger 46 of switch 44, causing it to open, this preventing the closing of the power circuit in any manner. As the tube travels into the "IurnacaTit is received by the openings 24 of the turrets 2'2 and as 'it continues its travel on the rollers 26, it strikes the trigger 54 of the switch El-causingitto close. The tube continues its movement until it strikes the spring bumper 84, which brings it, to rest with the trigger 15d :depressed and the trigger 4B -'b'a'ck in its normal position; 'completes 1 the :circuit to "the soil 18 f the magnetic contactors 116 through lines- 12,- closed switch T4, coil '80,

' vthe switch .52'to open asfit raisesirom vthetrigger r54, The circuit is maintained "through lines '86,

-8'8, switchlM, lines 404, 21116, 94, :cl'osed switch '44,1line 9B, closed-switch fili and-lines 98 and 100. When the turret 'rotated through the angulardistance :between two of the tubes :which it carries, switch 402 opens, deenergizing .rcoil 18 and opening .niagnetic contactor 16, thus fstop- ,pingniotor 40. At the same time, :switch N18 is closed, star.tingthe timeiswitch .66. Fllhe circuit tothe time. switch B is srcompleted'ithrough .lines 11 00, slt2,,, .l1i4, closed switch 108, and rlin'enllfi. -W1ienJthe turret reaches this positionnja heated tube is brought into icontactuwith .the rotating conyeyer rollers rwhich removeit from therright ,hand side of the furnace as seen Figure -1. Ash; .passesthrough the end of the .furnace, it contactstrigger 162-018 the switch 60, causing :it to open. switch is in series with switch 44 and, in its pemppsition, prevents theturret from rotating until the tube has ,passedthe switch. Normally another tube X -enters the .furnace after the heated tube passes the switch 60 and the cycle is repeated. Iiforany reason, another tube doesnotenter the furnace, the time-switch 66 wilLat-the-end of a predetermined time close switch NB. This closes the control circuit tothe coil 18, through lines 86, I20, closed switch 8, iineslol, m6, 8'4, closed switch 44, line as, closed switch 60, lines and Hill. Closing of the control circuit starts the motor 40 causing the turret to rotate as before and brings another.

hot tube to the conveyer rolls, When the switch fDB'is -openedby rotation of'the limit switch cam'58, the time switch '66 automatically sets to zero. The control circuit 'is then rea iivto be actuated by another tub'e entering the furnace or'tob'e "closed by thetim'e swith'BBin case no tubeis fed to the furnace.

, As the turret rotates; the"1owpoint"of each opening 24 "is changing 'and gravity causes the tube to rolltothe lowest point; Thus the tube has no one permanent or repeated point of contact while it is supported by the turrets and uniform heating results. The tubes are so supported in the turrets that they cannot pick up soft pieces of refractory.

While one embodiment of the invention has been shown and described, it will be apparent that other adaptationsand. modifications may be made without departing *from the scope of the following claims.

I claim:

1. A heating furnace for elongated articles comprisinga heating chamber, a horizontal shaft extending longitudinally through said chamber,

- a,p1urality of turrets mounted on said shaft, each of said Qturretshaving a plurality of angularly spaced openings therein, the opening in one turret being aligned with the openings in the other turrets, each group of aligned openings forming a support for one of the articles to be -heated, means for ie'edingathe artieles waidailly to :andxrrom the heating chamber, and. meansior rotating-sairl shait. 1

2.'A -heating furnace for elongated-a icles comprising a heating chamber, a horizontal shaft extending longitudinally through said chamber, a plurality of turrets moun'ted on said :shatt, said turrets having a plurality o'f angularlyspaced openings therein -for supporting' the ling thelheating :tu-rnace Ffor actuating sa.idisen- 0nd named means :to start rotation of -said :turrets, and means .forxstopping rotation of :said turretslaiter they have :rotated the :angular distance between two adjacent Iopenings. 1

4..A iheatin'g :furnace for elongated articles momprisingraheating :chamben a horizontal s'hait extending longitudinally through said chamber, a plurality of turrets mounted on said shaft; said turrets having a pluralityot angularly spaced openings therein for supportin :the articles to :be heated, -means for feeding the articles :to and fromthe heating chamber, means :ior rotating said shaft, means actuated by thearti'cle-enterlng the heating furnace for actuating said second named mea'ns 'to start rotation of said-turrets, means for stopping rotation of said turretslaiter they have rotated th'e angular 1 distance between two adjacent openings, and means aotuated byan :article lean mg the furnace for preventing operation of said second named means -until'thearticle has passed from the furnace.

5. A heating furnace for elongated-articles comprising 'aheatih'g chamber, a horizontal shaft extending "longitudinally through said chamber. a plurality of turrets mounted ou -said rshatt; said turrets ''having a plurality 'of =angularl-y spaced openings therein for supporting the articles to be heated,- means for feeding the artic'le's toand irom'theh'eitingchamber, m'eans ter rotating said :sheit, 'means actuated' by the 'article' eriter after they have rotated the angular distance between two adjacent openings, and a timer for actuating said second -named means after a predetermined time interval, said last named means also starting said timer in operation.

6. A heating furnace for elongated articles comprising a heating chamber, a horizontal shaft extending longitudinally through said chamber, a plurality of turrets mounted on said shaft, said turrets having a plurality of angularly spaced openings therein for supporting the articles to be heated, means for feeding the articles to and from the heating chamber, means for rotating said shaft, means actuated by the article entering the heating furnace for actuating said second named means to start rotation of said turrets, means for stopping rotation of said turrets after they have rotated the angular distance between two adjacent openings, a timer for actuating said second named means after a predetermined time interval, said last named means also starting said timer in operation, and means actuated by an article leaving the furnace for preventing operation of said second named means until the article has passed from the furnace, said timer being set at zero by rotation of said turret.

7. A heating furnace for elongated articles comprising a heating chamber, a horizontal shaft extending longitudinally through said chamber, a plurality of turrets mounted on said shaft, said turrets having a plurality of angularly spaced openings therein for supporting the articles tobe heated, an opening in the furnace for admitting articles to the furnace, a second opening for permitting discharging of articles from the furnace, said openings in the furnace being spaced apart the same angular distance as the openings in the turrets, means for feeding the articles to and from the heating chamber, and means for rotating said shaft.

8. A heating furnace for elongated articles comprising a heating chamber, a horizontal shaft extending longitudinally through said chamber,.

a plurality of turrets mounted on said shaft, said turrets having a plurality of angularly spaced openings therein for supporting the articles to be heated, an opening in the furnace for admitting articles to the furnace, a second opening for permitting discharging of articles from the furnace,

said openings in the furnace being spaced apart the same angular distance as the openings in the turrets, means for feeding thearticles to and from the heating chamber, means for rotating said shaft, and means actuated by the article entering the heating furnace for actuating said second named means to start rotation of said turrets.

openings therein for supporting the articles to be heated, an opening in the furnace for admitting articles to the furnace, a second opening for permitting discharging of articles from the furnace, said openings in the furnace being spaced apart the same angular distance as the openings in the turrets, means for feeding the articles to and from the heating chamber, means for rotating said shaft, means actuated by the article entering the heating furnace for actuating said second named means to start rotation of said turrets, and means for stopping rotation of said turrets after they have rotated the angular distance between two adjacent openings.

10. A heating furnace for elongated articles comprising a heating chamber, a horizontal shaft extending longitudinally through said chamber, a plurality of turrets mounted on said shaft, said turrets having a plurality of angularly spaced openings therein for supporting the articles to be heated, an opening in the furnace for admitting articles to the furnace, asecond opening, for per mitting discharging of articles from the furnace, said openings in the furnace being spaced apart the same angular distance as the openings in the turrets, means for feeding the articles to and from the heating chamber, means for rotating comprising a heating chamber, a horizontal shaft extending longitudinally through said chamber,

a plurality of turrets mounted on said shaft,said

turrets having a plurality of angularly spaced openings therein for supporting the articles to be heated, an opening in the furnace for admitting articles to 'the furnace, a second opening for permitting discharging of articles from the furnace,

said "openings in the furnace being spaced apart the same angular distance as the openings in the turrets, means for feeding the articles to and from the heating chamber, means for rotating said shaft, means actuated by the article entering the heating furnace for actuating said second named means to start rotation of said turrets, means for stopping rotation -of said turrets after they have rotated theangular distance between two adjacent openings, and a timer for actuating said second named means after a predetermined time interval, said last named means also starting said timer in operation.

12. A heating furnace for elongated articles comprising a heating chamber, a horizontal shaft extending longitudinally through said chamber, a plurality ,of turrets mounted on said shaft, said turrets having a plurality of angularly spaced apart the same angular distance as the openings in the turrets, means for feeding the articles to and from the'heating chamber, means for rotating said shaft, means actuated by the article entering the heating furnace for actuating said second named means to start rotationof said turrets, means for stopping rotation of said turrets after they have rotated the angular'distance between two adjacent openings, a timer for actuating said second named means after apredetermined time interval, said last named means also starting said timer in operation, and means actuated by an article leaving the furnace for preventing operation of said second named means until the article has passed from the furnace, said timer being set at zero by rotation of said turret.

ANDREW' F. KRITSCHER. 

